Spectroscopic imaging combines digital imaging and molecular spectroscopy techniques, which can include Raman scattering, fluorescence, photoluminescence, ultraviolet, visible and infrared absorption spectroscopies. When applied to the chemical analysis of materials, spectroscopic imaging is commonly referred to as chemical imaging. Instruments for performing spectroscopic (i.e. chemical) imaging typically comprise image gathering optics, focal plane array imaging detectors and imaging spectrometers.
In general, the sample size determines the choice of image gathering optic. For example, a microscope is typically employed for the analysis of sub micron to millimeter spatial dimension samples. For larger objects, in the range of millimeter to meter dimensions, macro lens optics are appropriate. For samples located within relatively inaccessible environments, flexible fiberscopes or rigid borescopes can be employed. For very large scale objects, such as planetary objects, telescopes are appropriate image gathering optics.
Conventional imaging system include a slide for receiving the sample, a light source for illuminating the sample with a plurality of photons, a lens for receiving the photons scattered (or emitted) by the sample, a tunable filter and an image sensor for forming a three dimensional image of the sample. During operation, the sample is placed on a microscopic slide or a Petri dish and placed at a designated location where photons emitted or scattered from the sample can be collected by an objective lens. The conventional imaging spectrometers are configured to obtain an image of a sample in a homeostasis. That is, the conventional imaging systems are directed to detecting an image from a samples in a state of physical and/or chemical equilibrium with a tendency to remain in such state. There is a need for a method and apparatus for chemical imaging of a dynamic system.